Question:
An open knife edge of mass m is dropped from a height $h$ on a wooden floor. If the blade penetrates distance $s$ into the wood, the average resistance offered by the wood to the blade is
An open knife edge of mass m is dropped from a height $h$ on a wooden floor. If the blade penetrates distance $s$ into the wood, the average resistance offered by the wood to the blade is
Updated On: Jan 10, 2024
- $ mg $
- $ mg(\frac{h}{s}) $
- $ mg\left( 1-\frac{h}{s} \right) $
- $ mg{\left( 1+\frac{h}{s} \right)}^{2} $
Hide Solution
Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Velocity at the time when knife edge strikes wooden floor is
$ \sqrt{2gh} $ .
The velocity of $ \sqrt{2gh} $ is reduced to zero in a distance $s$.
If $F$ is the average retardation, then by work-energy theorem, we have
$ 0-\frac{1}{2}mv^{2}=-Fs $
$ \Rightarrow $ $ F=mg\frac{h}{s} $
Was this answer helpful?
1
0
Top Questions on work, energy and power
- Two heaters A and B have power rating of 1 kW and 2 kW, respectively. Those two are first connected in series and then in parallel to a fixed power source. The ratio of power outputs for these two cases is :
- NEET (UG) - 2024
- Physics
- work, energy and power
- An object moving along horizontal x-direction with kinetic energy \(10 \, \text{J}\) is displaced through \(\mathbf{x} = (3\mathbf{i}) \, \text{m}\) by the force \(\mathbf{F} = (-2\mathbf{i} + 3\mathbf{j}) \, \text{N}\). The kinetic energy of the object at the end of the displacement \(\mathbf{x}\) is:
- NEET (UG) - 2024
- Physics
- work, energy and power
- An object falls from a height of 10 m above the ground. After striking the ground it loses $50\%$ of its kinetic energy. The height upto which the object can rebounce from the ground is:
- NEET (UG) - 2024
- Physics
- work, energy and power
- At any instant of time t, the displacement of any particle is given by 2t – 1 (SI unit) under the influence of force of 5N. The value of instantaneous power is (in SI unit):
- NEET (UG) - 2024
- Physics
- work, energy and power
- A player caught a cricket ball of mass 150 g moving at a speed of 20 m/s. If the catching process is completed in 0.1 s, the magnitude of force exerted by the ball on the hand of the player is:
- JEE Main - 2024
- Physics
- work, energy and power
View More Questions
Questions Asked in AMUEEE exam
- The ratio of the half-life time $ (t_{1/2}) $ , to the three quarter life-time, $ (t_{3/4}) $ , for a reaction that is second order
- AMUEEE - 2018
- Order of Reaction
- $ 0.002\, M $ solution of a weak acid has an equivalent conductance $ (\wedge) 60\, ohm^{-1}\, cm^{2}\, eq^{-1} $ . What will be the $ pH $ ? (Given : $ \wedge = 400 \, ohm^{-1} \, cm^{2} \, eq^{-1} $ ]
- AMUEEE - 2018
- Electrochemistry
- The electrode potential, $ E^{\circ} $ , for the reduction of $ MnO^{-}_{4} $ to $ Mn^{2+} $ in acidic medium is $ +1.51\, V $ . Which of the following metal(s) will be oxidised? The reduction reactions and standard electrode potentials for $ Zn^{2+}, Ag^{+} $ , and $ Au^{+} $ are given as $ Zn^{2+} (aq) +2e \to Zn(s), E^{\circ} = -0.762\, V $ $ Ag+ (aq) +e {\rightleftharpoons} Ag (s), E^{\circ}=+0.80 \,V $ $ Au^{+} (aq) +e {\rightleftharpoons} Au(s), E^{\circ}+1.69\,V $
- AMUEEE - 2018
- Electrochemistry
- Three particles, two with masses $ m $ and one with mass $ M $ , might be arranged in any of the four configurations shown below. Rank the configurations according to the magnitude of the gravitational force on $ M $ , least to greatest
- AMUEEE - 2018
- Gravitation
- The $ EAN $ value $ y \left[Ti\left(\sigma-C_{6}H_{5}\right)_{2}\left(\pi-C_{5}H_{5}\right)_{2}\right]^{0} $ is
- AMUEEE - 2018
- coordination compounds
View More Questions
Concepts Used:
Work, Energy and Power
Work:
- Work is correlated to force and the displacement over which it acts. When an object is replaced parallel to the force's line of action, it is thought to be doing work. It is a force-driven action that includes movement in the force's direction.
- The work done by the force is described to be the product of the elements of the force in the direction of the displacement and the magnitude of this displacement.
Energy:
- A body's energy is its potential to do tasks. Anything that has the capability to work is said to have energy. The unit of energy is the same as the unit of work, i.e., the Joule.
- There are two types of mechanical energy such as; Kinetic and potential energy.
Read More: Work and Energy
Power:
- Power is the rate at which energy is transferred, conveyed, or converted or the rate of doing work. Technologically, it is the amount of work done per unit of time. The SI unit of power is Watt (W) which is joules per second (J/s). Sometimes the power of motor vehicles and other machines is demonstrated in terms of Horsepower (hp), which is roughly equal to 745.7 watts.
- Power is a scalar quantity, which gives us a quantity or amount of energy consumed per unit of time but with no manifestation of direction.